The wireless cellular network adopts cellular-form network architecture to provide a communication service such as voice and data and the like for a mobile user. Typically, a cell provides wireless communication transmission coverage of a certain range. Specifically, the cell having the largest wireless communication transmission coverage radius is a Macrocell. A plurality of Macrocells may implement wide-range seamless wireless communication transmission coverage. A base station supporting the Macrocell is called a Macrocell base station, its emission power is larger, and its antenna arrangement height is higher, e.g. an eNodeB (eNB) in a 3GPP LTE or a 3GPP LTE-A network, etc.
In order to increase the capacity of the wireless cellular network and to improve the wireless communication service quality in its coverage area, a cell with a smaller transmission radius than the Macrocell (e.g. Microcell, Picocell, Femtocell and etc.) may be used in a hotspot area and may be used indoors. The base station of the cell having a smaller transmission radius than that of the Macrocell typically has a smaller emission power and a lower antenna arrangement height than those of the Macrocell base station.
Typically, the above cell having various transmission radii may be present in a particular potion of area simultaneously. At this time, the base station of the cell having various transmission radii may provide overlapped wireless network coverage of at least two layers in the area where the coverage thereof overlaps, i.e. the cell having the larger transmission radius (e.g. the Macrocell) provides the wireless network coverage of one layer and the cell having the smaller transmission radius (e.g. the Femtocell) provides the wireless network coverage of another layer.
In embodiments of the present invention, to facilitate description, the cell having the larger transmission radius in the wireless cellular network having the wireless network coverage of at least two layers is called a major cell, while the wireless cell having the smaller transmission radius therein is called a small cell. Specifically, the transmission radius of the major cell is larger than that of the small cell. For example, in the wireless cellular network where the coverage of the Macrocell overlaps that of the Microcell or that of the Picocell or that of the Femtocell, the major cell refers to the Macrocell, and the small cell refers to the Microcell, the Picocell or the Femtocell; in the wireless cellular network where the coverage of the Microcell overlaps that of the Picocell or that of the Femtocell, the major cell refers to the Microcell, and the small cell refers to the Picocell or the Femtocell; while in the wireless cellular network where the coverage of the Picocell overlaps that of the Femtocell, the major cell refers to the Picocell, and the small cell refers to the Femtocell. Correspondingly, the base station in the major cell is called a major base station, e.g. a Macrocell base station; while the base station of the small cell is called a small base station, e.g. a Home eNodeB (HeNB) supporting the Femtocell coverage in the 3GPP LTE or the 3GPP LTE-A network, and may be easily disposed in home or office by the user.
Within the area having the overlapped wireless network coverage of at least two layers, the UE (User Equipment) of the mobile user may select to access the major cell or the small cell. For example, in the 3GPP LTE or the 3GPP LTE-A network, the eNB supports the Macrocell coverage, while the HeNB supports the Femtocell coverage. In the area where the coverage of the eNode B overlaps that of the HeNB, the UE may select to access the eNB or the HeNB. In embodiments of the present invention, to facilitate description, the UE accessing the major base station (e.g., Macrocell) is collectively called Major-cellular User Equipment (MUE), while the UE accessing the small base station is collectively called Home User Equipment (HUE).
In such communication environment having the wireless network coverage of at least two layers as described above, the spectrum occupied by the two-layer wireless network may be shared with each other, and the spectrum range shared by the two-layer wireless network may be all or part of the available spectrum. For example, in the case that the available spectrum bandwidth of the two-layer wireless network is 20 MHz in total, if the spectrum range shared by the two-layer wireless network is all the available spectrum range, the major cellular network and the small cellular network may both use the spectrum resources of such 20 MHz; while if the spectrum range shared by the two-layer wireless network is part of the available spectrum range, the major cellular network may use part of the spectrum resources (e.g. 15 MHz), while the small cellular network may use all the 20 MHz spectrum resource.
When the spectrum range occupied by the major cellular network and the small cellular network is shared, there is co-channel interference between the two-layer wireless network. Thus, in a Frequency Division Duplex (FDD) system, the interference between the two-layer wireless network may be divided into four types of uplink and downlink interference as follows, i.e. including: the downlink interference on the HUE from the major base station, the downlink interference on the MUE from the small base station, the uplink interference on the major base station from the HUE and the uplink interference on the small base station from the MUE. When the MUE in an active state is communicating with the major base station, if the MUE is relatively close to the small base station, the MUE may suffer more serious downlink interference from the small base station, which may result in the communication between the MUE and the major base station to be interrupted. Further, when a HUE in an active state is communicating with a small cellular base station, if the HUE is relatively close to a big base station, the HUE may suffer more serious downlink interference from the big base station, which may result in the communication between the HUE and the small cellular base station to be interrupted.